WHMIS Training for Occupational Health & Safety (Canada)

WHMIS Hazard Classes

 

Since the Hazardous Products Regulations replaced the Controlled Products Regulations in Canada, WHMIS has primarily used the UN Globally Harmonized System (GHS) pictograms. These pictograms, easily recognizable by their red diamond-shaped border, attract workers' attention and inform them of the hazards posed by the products. These hazards are divided into 2 groups: physical hazards and health hazards.

Physical Hazards

 

Physical hazards are hazards that can cause damage to the immediate environment of the products, through mechanical or chemical action. Physical hazards can also seriously injure workers who are exposed to them. WHMIS groups physical hazards under 5 pictograms, in addition to hazards that are not identified by a pictogram.

Exploding Bomb

This pictogram warns the worker that the product puts him or her at risk of an explosion, that is, a chemical reaction generating gases at a speed, temperature and pressure that could cause harm.

Explosives are not regulated under WHMIS, as they are regulated in Canada by the Explosives Act. However, some substances that are not legally explosives may still pose an explosion hazard. The following WHMIS hazard classes require the exploding bomb pictogram to be displayed:

• Self-reactive substances - Types A and B
• Organic peroxides - Types A and B

When this pictogram is present on a product, all necessary precautions must be taken to prevent detonation or deflagration of the substance. The product must be protected from heat, flames, sparks, static electricity and shock. They must be protected from light and kept cool, often refrigerated in an explosion-proof refrigerator, and only trained personnel should have access to them. The quantity of these substances that are kept in a workplace should be kept to a minimum.

Gas Cylinder

 

The gas cylinder pictogram is present when a product is a pressurized container, except for aerosols. This pictogram indicates to the user that the contents are under pressure, and that there is a risk of significant damage if the container is opened, broken or mishandled.

Gas cylinders are often the products that carry this pictogram. If broken, a gas cylinder can literally go off like a rocket, causing considerable damage to anything in its path. The WHMIS hazard classes that require this pictogram to be displayed are:

• Gases under pressure
  • Compressed gases
  • Liquefied gases
  • Refrigerated liquefied gases
  • Dissolved gases
• Chemicals under pressure

When handling, transporting or storing a product that bears the gas cylinder symbol, care must be taken to avoid any situation that could lead to the rupture of the container. Cylinders must be kept upright and secured to prevent them from falling. Containers must be kept away from heat and sunlight to avoid an increase in internal pressure that could lead to an explosion of the container.

Flame

The flame pictogram is the WHMIS pictogram that groups together the most different hazard classes. It indicates, quite generally, a fire hazard.

There are 11 separate hazard classes that are associated with the flame pictogram. These classes are:

• Flammable gases - Categories 1A, 1B, Chemically unstable gases A and B, and 1A Pyrophoric gas
• Aerosols - Categories 1 and 2
• Flammable liquids - Categories 1, 2 and 3
• Chemicals under pressure - Categories 1 and 2
• Flammable solids - Category 1
• Pyrophoric liquids
• Pyrophoric solids
• Self-heating substances
• Substances which, in contact with water, emit flammable gases
• Self-reactive substances - Types B, C, D, E, F
• Organic peroxides - Types B, C, D, E, F

When handling products bearing the flame pictogram, particular care should be taken to keep them away from open flames, heat sources and sparks. Measures should also be taken to avoid shocks and static electricity. Mixing these products with oxidizing products should also be avoided, as these mixtures increase the risk of ignition.

Some of these substances also require special precautions, such as pyrophoric liquids and solids, which must be stored under an inert atmosphere. Materials that, in contact with water, emit flammable gases should be kept dry, such as in a desiccator or immersed in oil, to avoid contact with water or moisture in the air.

The storage of products bearing the flame pictogram is a complex issue due to the wide range of hazard classes grouped together. Not all substances bearing the flame symbol are compatible with each other. Self-heating materials, for example, cannot be stored with flammable materials. The storage of materials bearing the flame pictogram is often problematic, and further study is often required for the safe storage of these substances. It is often easier to rely on the classification of the products in the transport of dangerous goods for their storage.

Flame on a Circle

The flame pictogram on a circle represents products that present a risk due to their oxidizing action. In other words, these are products that are not combustible, but that can cause or aggravate a fire due to their property of providing oxygen. There are three hazard classes under this pictogram:

• Oxidizing gases
• Oxidizing liquids
• Oxidizing solids

Products that bear this pictogram must be kept away from flammable products and combustibles. In the event of a fire, a fire that reaches oxidizing products would accelerate and grow, which must be avoided at all costs. Contact of these materials with flammable products is also to be avoided, as this can cause a fire or even an explosion. Some oxidizing products even have an oxidizing power powerful enough to start a fire on contact with simple combustible materials, such as wood or paper. For this reason, oxidizers should not be stored in cardboard boxes or on wooden pallets and shelves.

Corrosion

The corrosion pictogram is the only WHMIS pictogram that is used to identify both physical and health hazards. In this section, we are only interested in physical hazards. Health hazards will be covered in the next section.

In the case of physical hazards, this pictogram represents products that cause damage to metals through chemical action. Only one hazard class is associated with this pictogram:

- Materials that are corrosive to metals

When handling a substance that is corrosive to metals, it is logical to prevent it from encountering metals. This involves quickly cleaning up any spilled substance to prevent it from reaching and attacking surrounding metal structures. Another point of vigilance is the container in which the product is stored or transferred, which must be corrosion resistant. Storing these substances in a metal container is prohibited to avoid container failures that could lead to a spill.

Another point of the substances identified by the corrosion pictogram is that it includes acidic, basic, and neutral substances. However, acids and bases are incompatible. During storage, special attention must therefore be paid to the separation of these substances. Indeed, mixing an acid and a base can cause a violent exothermic reaction. The heat generation can cause a fire and projections of non-neutralized corrosive substances in all directions, thus increasing the damage and risks. Safe handling of acids and bases should also avoid mixing these substances, or at least ensure that they are mixed in a way that controls the reaction.

Hazards without Pictograms

There are several classes of physical hazards in WHMIS that, even though they present a hazard, do not require the display of a pictogram. These are the following hazard classes:

When handling a product that does not have a pictogram, it is therefore advisable to check the label to ensure that the product does not fall into one of these hazard categories. This allows you to take appropriate measures to protect yourself.

Physical Hazards Not Otherwise Classified

Finally, one last class of physical hazards deserves a mention: Physical Hazards Not Otherwise Classified (PHNOC). This class allows for mentioning a physical hazard specific to the product that would not be present in the regulation. One could think, for example, of a product that makes surfaces extremely slippery and risks causing falls during a spill.

No specific pictogram is provided for this class of hazard. However, it is permitted in Canada to use one of the WHMIS pictograms to warn of a such a hazard, if this pictogram is appropriate. A PHNOC that could cause a fire, for example, could be identified by the flame pictogram.

Health Hazards

 

Health hazards are hazards that affect human health. Their actions can be immediate or long-term, localized or systemic, and sometimes even lethal. WHMIS groups health hazards under 5 pictograms, in addition to hazards that are not identified by a pictogram.

Corrosion

This pictogram informs the worker that the product can cause corrosion of the skin, eyes or even the respiratory tract. Corrosion is characterized by the appearance of irreversible lesions, such as necrosis, burns, ulcerations, bleeding and blisters.

It is important to know that an acidic product and an alkaline product will not act in the same way on your skin. In fact, the acid will be felt immediately by a pain signal. For a base, there will rather be a saponification reaction with the skin; the base transforms your skin into soap! This reaction, at the time, is not painful although the damage is triggered.

The WHMIS hazard classes that require the display of this pictogram are:

• Skin corrosion - Categories 1A, 1B and 1C
• Serious eye damage - Category 1
• Health hazards not otherwise classified - Corrosion - Category 1 (for respiratory tract corrosion)

Regardless of whether your product is acidic or alkaline, when this pictogram is present, body and eye wash stations must be in the vicinity of the handling of these products. The ANSI Z358.1-2014 standard must be respected during installation.

The use of protective equipment such as gloves, safety glasses and any other equipment to reduce the risks of contact with the product is also necessary.

In terms of storage, the considerations discussed in the section on materials corrosive to metals also apply here. Since corrosive substances can be acidic or basic, special attention must be paid to incompatibilities.

Skull and Crossbones

This pictogram warns the worker that he is in the presence of a product with acute toxicity. Acute toxicity is characterized by adverse effects that can lead to death following the administration of a single dose (or several doses spread over a 24-hour interval).

WHMIS considers ingestion, inhalation, and skin contact as routes of exposure to a product. For inhalation toxicity, three types of exposure are possible: exposure to gas, exposure to vapors, or exposure to dust and mists. It should be noted that a product that is toxic by skin contact can kill without leaving a trace or burn on the skin. Some products can also release a toxic gaseous substance when they contact water.

The criteria used to determine a product's dangerousness are the LD50 (lethal dose for 50% of the population) and the LC50 (lethal concentration for 50% of the population). The smaller the dose required to poison, the more dangerous the product.

The WHMIS hazard classes that require the display of this pictogram are:

• Acute toxicity - Categories 1, 2 and 3
• Acute toxicity - Categories 1, 2 and 3
• Acute toxicity - inhalation - Categories 1, 2 and 3

As with corrosive products, when this pictogram is present, body and eye showers must be close to the handling zone of toxic products. All means must be taken to minimize exposure to the product.

It is important to store toxic products in a cool and well-ventilated place. Toxic products must be kept away from oxidizing materials, strong oxidants and all incompatible products. They must also be kept away from heat sources or places where the risk of fire is high.

Health Hazard

This pictogram is used to designate products that are seriously harmful to health. It is used for 7 WHMIS health hazard classes:

• Respiratory sensitization
• Germ cell mutagenicity
• Carcinogenicity
• Reproductive toxicity - Categories 1A, 1B and 2
• Specific target organ toxicity - single exposure - Categories 1 and 2
• Specific target organ toxicity - repeated exposure
• Aspiration hazard

Since this pictogram is used for several hazard classes, it is important to read the label and consult the Safety Data Sheet (SDS) to know what hazard(s) you will be exposed to when handling this product.

Except for Specific Target Organ Toxicity - Single Exposure and Aspiration Hazard, these are hazards that will affect your health over the long term. It is therefore very important to use the appropriate personal protective equipment when handling these products, as the damage may not appear for several years. Again, reducing exposure to these products is the best option.

Products with this pictogram should be stored in a cool, well-ventilated area, away from your other hazardous products.

Exclamation Point

This pictogram indicates a product that is harmful to health. The WHMIS classes and categories associated with the exclamation point pictogram are:

• Acute toxicity - oral - Category 4
• Acute toxicity - dermal - Category 4
• Acute toxicity - inhalation - Category 4
• Skin irritation - Category 2
• Eye irritation - Category 2A
• Skin sensitization
• Specific target organ toxicity - single exposure - Category 3
  • Narcotic effect
  • Respiratory tract irritation

Since this pictogram is used for several hazard classes, it is important to read the label and consult the safety data sheet (SDS) to know what hazard(s) you will be exposed to when handling the product. Indeed, you will not protect yourself in the same way from a harmful product as from an irritant or sensitizing product. Products with this pictogram should be stored in a cool, well-ventilated area, away from your other hazardous products.

Biological Hazards

The Biohazardous Infectious Materials pictogram is unique to Canada. That is why it is not a diamond-shaped icon with a red border like other WHMIS pictograms. It is important to read product labels with this pictogram carefully to understand the hazard you will be exposed to. The hazard statements will vary depending on the infectious material.

Hazards without pictograms

There are a few WHMIS health hazard classes that, despite being hazardous, do not require a pictogram to be displayed. These are the following hazard classes:

• Eye irritation - Category 2B
• Reproductive toxicity - Effect on or via breastfeeding

Since some hazards do not require a pictogram, you should always read the product label before using it to be aware of the hazard(s) to which you will be exposed.

Health hazards not otherwise classified

Finally, one last class of health hazards must be mentioned: Health Hazards Not Otherwise Classified (HHNOC). This class allows you to mention a health hazard specific to the product that would not be present in the regulations.

No specific pictogram is provided for this hazard class. However, it is permitted in Canada to use one of the WHMIS pictograms to warn of a hazard, if this pictogram is appropriate.

As mentioned above when there is respiratory tract corrosion the product can be classified as Health Hazards Not Otherwise Classified - Corrosion - Category 1 and the corrosion pictogram added.